Previous attempts to introduce biaxial orientation into tubular materials formed from orientable thermoplastic polymeric materials by drawing them over an expanding former have involved only a limited degree of expansion in the hoop direction i.e. in the direction perpendicular to the axis of the tube. British Patent 1456222 describes a process and apparatus used to draw a tube of thermoplastic polymer over an expanding former in order to calibrate the internal dimensions of the tube. The processes described require the application of a liquid lubricant to the inner surface of the workpiece prior to its passage over the former. In our British Patent 2156733 we have described processes in which the tubular material is drawn simultaneously through a die and over an expanding former.